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Lecture 11b-19 November 2014
This lecture is based largely on CHAPTER 23 IN KRAUSE'S FOOD NUTRITION AND DIET THERAPY (ON RESERVE IN LIBRARY) AND CHAPTERS 7,8,9 IN ROLFES ET AL.
Final exam-120 multiple choice-120 marksfrom vitamins to end of course
-4 short answer questions-15 points each for a total of 60 points
covers whole course
-3 hours- 180 marks
Lecture 11
OutlineMetabolic aspects of Nutrition and fitness/Sports Nutrition
Energy production ATP Anaerobic pathway Aerobic pathway Energy continuum Sources of fuel
Outline of lecture 11
Energy production
Substrate choice
Intensity Duration Effect of training Diet
Outline of lecture 11
Nutritional Requirements Fluid Fluid Balance Fluid Absorption
Factors affecting fluid absorption Requirements Short duration Endurance
Outline of lecture 11
Nutritional Requirements Carbohydrate Types of carbohydrate
Pre-event
During event Post-event
Outline of lecture 11
Nutritional Requirements Protein Endurance
Resistance Exercise
Amino acid supplementation
Outline of lecture 11Nutritional Requirements Lipid
Minerals Iron Calcium Vitamins Anti-oxidant vitamins and B-
carotene C E B vitamins
Outline of lecture 11
Regulation of metabolism
Energy production
Energy continuum
All pathways can produce ATP
At the beginning of any exercise whatsoever anaerobic metabolism is in place to produce ATP
If the person continues to exercise at a
moderate level for a prolonged period then the aerobic pathway will become the predominant pathway for energy production (eg marathon run)
Energy production Energy continuum
If the person continues to exercise for a short period of high power and high intensity then the anaerobic pathway will become the
predominant pathway for ATP energy production(eg 100 metre sprint)
Production of ATP is therefore a continuum that depends on the:
-availability of oxygen -the capacity for intensity of the exercise -the capacity for the duration of the exercise
Energy production Energy continuum
There is an inverse relation between the capacity for intensity and the capacity for the duration of the exercise
-one cannot perform high intensity exercise over a long period of time
-the duration increases as the intensity
drops and as the intensity of the exercise increases the duration of that exercise drops
Energy production
Energy continuum
-the aerobic pathway cannot tolerate the same level of intensity as the duration increases due to the decreased availability of oxygen and the
production of lactic acid
Energy production
Energy continuum-as the intensity increases the power output
decreases POWER = WORK/TIME
WORK = FORCE X DISTANCE
-as the intensity decreases the power output increases
POWER = WORK/TIME WORK = FORCE X DISTANCE
Energy production Sources of fuel
as the duration increases more energy is obtained from fat (fatty acids) and as the duration decreases and the intensity increases more energy is obtained from carbohydrate
carbohydrate is obtained from dietary carbohydrate, glycogen or amino acids (amino acids can be synthesized to glucose-this process is known as gluconeogenesis)
Energy production Sources of fuel
Kreb’s cycle-alanine is the main amino acid contributing to the Krebs cycle
-3 carbon units of glucose
contributing to the Krebs cycle
-2 unit carbons of fatty acids
contributing to the Kreb’s cycle
Energy production Sources of fuel
Kreb’s cycle
-all of these substrates are used most of the time however the intensity and duration of the exercise dictates the relative rates of substrate utilisation
Energy production
Substrate choice
Intensity- high intensity must rely on carbohydrate
Because oxygen is not available for high intensity exercise glycogen must be utilized
Glycogen catabolism is much higher than with aerobic activity- 18-19 times faster (2 ATP versus 36-38 ATP)
-Energy production
Substrate choice
Intensity-Hockey, basketball for eg favour higher glycogen utilization rates than marathon running while moderate intensity exercise favours 50/50 split of (glycogen)/(glucose-lipid) use
-Energy production
Substrate choice Low intensity exercise like walking is entirely
aerobic and most of the ATP comes from lipid
Fat yields 4.65 kcal / L of oxygen consumed vs for carbohydrate a yield of 5.01 kcal/L of oxygen consumed
-thus in longer term exercise carbohydrate use is favoured
Once the glycogen stores are depleted then that is the end of the high intensity exercise
Energy production
Substrate choice Duration-the longer the event the greater the
proportion of lipid used to produce ATP
-consequently the lower the amount
of lactate produced
Effect of training-increase number of mitochondria and activity of ATP producing enzymes
Energy production
Substrate choice Diet-dictated by fuel utilization for a particular
event
-high intensity requires more carbohydrate in the diet
-lower intensity requires more lipid in the diet however do not consume a high fat diet-
crowd out carbs and run the risk of heart disease
Class exercise
Explain the effects of exercise intensity, duration and training on substrate utilisation.
Break
Nutritional Requirements Fluid Fluid Balance
Important for maintaining blood flow which in turn is important for supplying blood to skin and hence temperature control
75 percent of energy goes out as heat-therefore must sweat
regulated by kidney, sweat loss, feces, respiration and fluid intake
important to consume sodium and water to replace water lost as sweat-thus blood sodium is maintained and therefore so are hormone levels which limit the rate of urine production
Nutritional Requirements
Fluid Absorption Factors affecting fluid absorption -glucose and sodium travel across
intestine on same carrier
Nutritional Requirements Fluid Requirements Short duration
-if several heats before actual race this can be problem for hydration
- plain water dilutes the blood, increases
urination and results in dehydration Endurance
-plain water lowers blood glucose concentrations thus increasing the demand on muscle glycogen
Nutritional Requirements
Carbohydrate Types of carbohydrate
After glycogen runs out must use gluconeogenesis to maintain blood glucose levels
Glycogen loading is important-eg pasta diet some have suggested complex carbs are better at glycogen loading in muscle than are simple carbs but this is debatable
Nutritional Requirements
CarbohydratePre-event
Takes care of hunger Maintains adequate blood glucose levels for
event During event Maintains blood glucose and delays fatigue Post-event Builds glycogen up in muscle after
depletion
Nutritional Requirements
Protein
Endurance Less required than for resistance events Resistance Exercise More required than for endurance events -muscle mass issue
Nutritional Requirements
Protein
Amino acid supplementationA waste of time- eat more calories in accordance with Canada’s food guide to meet increased energy demands and this will easily meet added protein/amino acid requirements
Can lead to dehydration, loss of urinary calcium, weight gain and stress on the kidney and liver
Nutritional Requirements
Lipid -supplies essential fatty acids
-important energy source during endurance exercise
-less important as an energy source for high intensity exercise
Class exercise
How do the 6 nutrient classes work together to allow:
a) Aerobic exerciseb) Anaerobic exercise
Break
Nutritional Requirements
Minerals Iron -oxygen carrying-hemoglobin and
myoglobin
-part of electron transport chain-ATP Calcium -bone mass
Nutritional RequirementsVitamins Anti-oxidant vitamins and -carotene, vitamin C
and E-exercise produces increased amount of lipid peroxides and free radicals-damage muscle
-supplements are not required-no evidence
that they improve performance B vitamins -important co-enzymes in energy production
-B12-supplement required in strict vegans
Regulation of Metabolism
Oxygen supplyAs intensity of exercise increases the oxygen supply becomes limiting-with training one can supply more oxygen
Substrate supply
Availability of co-enzymes
Hydration
Mechanisms described for each of the nutrient classes
Class exercise
What is the major direction of metabolism
during exercise?
after exercise?
Why ?
